How To Add Custom HTML Javascript Code in Blogger

Blogger provide you a gadget to use custom javascript/HTML code at your blog.
with this gadget, you can easily use any kind of javascript or HTML code at your blog. this is really a useful gadget to add custom HTML javascript code in blogger blog.
by using custom javascript/HTML gadget you can easily show Adsense ads, Facebook like us plugin or your own code.
if you want to know how to show